2,2 -Dipyridyl Disulfide/Triphenylphosphine

LACTONIZATION Boron trifluoride etherate. 2-Chloro-l-methyl-pyridinium iodide. 2,2 -Dipyridyl disulfide-Triphenylphosphine. Phosphorus pentoxide-Methanesulfonic acid. Triphenylphosphine-Diethyl azodicarboxylate. 

LACTAMS Di-n-butyltin oxide. Ily-droxylamine-O-sulfonic acid. Iodine azide. Sodium eyanoborohydride. (3-LAC TAMS Cyanuric chloride. Grignard reagents. Ion-exchange resins. Lithium phenylethynolate. Sodium dicarbonyl-cyclopentadienylferrate. Titanium(lll) chloride. Titanium(IV) chloride. Tri-phenylphosphino-Carbon tetrachloride. Triphenylphosphine-Die thyl azodicar-boxylate. Triphenylphosphine-2,2 -Dipyridyl disulfide. 

Benzylamino)acetonitrile, 29 4-Pyrrolidinopyridine, 262 Triphenylphosphine-2,2 -Dipyridyl disulfide, 332 Zinc iodide, 350 Lactonization (see also Enol lactonization)... 

Benzoylthio-3-nitropyridine (1). The reagent is generated in situ by reaction of 3,3 -dinitro-2,2 -dipyridyl disulfide with benzoic acid and triphenylphosphine in... 

In 1974, Corey and Nicolaou [14] found that hydroxy acid 11 can be efficiently activated by 2,2 -dipyridyl disulfide (DPDS). As shown in Scheme 5, in the presence of triphenylphosphine, 11 reacts with DPDS yielding 2-pyridinethiol ester 12. The proton transfer from hydroxyl group to carbonyl in 2-pyridinethiol ester 12 is facilitated by the basic nitrogen of the pyridine nucleus and a dipolar intermediate 13 is formed. Then a facile, electrostatically driven cyclization occurs. 

The reaction depicted was run in THF at 0 C, other solvents having been found to be inferior. The S-(2-pyridyl) thioates may be prepared through reaction of the corresponding acid chloride and 2-pyridine-thiol in the presence of a tertiary amine. They are also available directly from carboxylic acids by reaction with 2,2 -dipyridyl disulfide (Aldrithiol-2) and triphenylphosphine. In the case illustrated above, protection of the ketone would seem unnecessary if Grignard addition was selective for the thiol ester however, the starting material, 5-(2-pyridyl) y-oxopentanethioate, is not stable to the lactonization shown in equation (18). 

Another efficient method seems to be Mukaiyama s redox condensation, which has found widespread application in total syntheses of natural products. Originally 5-(2-pyridyl)carbothioates (18), obtained from carboxylic acids, 2,2 -dipyridyl disulfide and triphenylphosphine (equation 8), were used in follow-up reactions. The use of (18) has been reviewed in the literature. - ... 

Phosphorylation of alcohols and amines forming mixed esters of phosphoric acid and phosphorami-dates, respectively, is effected by triphenylphosphine and 2,2 -dipyridyl disulfide. The reaction passes through a triphenylphosphonium phosphate of type (68 equation 44) as an active intermediate. Formation of an intemucleotide linkage can be achieved by this method. °° Dimerization of monoesters of phosphoric acid producing dialkyl pyrophosphates is achieved using tributylphosphine and dibenzoyl-ethylene or p-quinonedibenzimide (equation 45). A phosphonium phosphate is the active intermediate of this reaction. ... 

Peptide coupling. Mukaiyama et al. have used the combination of triphenylphosphine and 2,2 -dipyridyl disulfide (supplier Pierce) to effect coupling of an N-protected amino acid with an amino acid ester. The condensation involves oxidation-reduction ... 

PEPTIDE SYNTHESIS r-Amyl chloro-formate. f-Butyl azidoformate. Diethyl methyleneraalonate. N-Ethoxycarbonyl-2-ethoxy-l,3-dihydroquinoline. Hexamethylphosphoric triamide. 1-Hydroxybenzo triazole. Triphenylphosphine—2,2 -Dipyridyl disulfide. Triphenyl phosphite. 

Macrocyclic lactones. Corey et al. have published several more examples of the conversion of co-hydroxyalkanoic acids to macrocyclic lactones by use of 2,2 -dipyridyl disulfide and triphenylphosphine. Several lactones in the prostaglandin series have been prepared, for example, (1) and (2). The process has been applied to even more complex natural products and has also been used... 

Lactonization. The disulfide 1 (7, 141) was used instead of 2,2 -dipyridyl disulfide by Corey and Bhattacharyya in a total synthesis of macrocyclic lactone enterobactin (2) involved in the transport of iron in certain bacteria. The lactone ring was constructed from three L-serine units, with protection of the amino group as the CBZ group and of the hydroxyl group as the THP ether. The three serine units were condensed in steps using 1 and triphenylphosphine to give the... 

Ring closure of the )S-thiolallcanoyl amino acid (40) was facilitated hy treatment of 2,2 -dipyridyl disulfide in the presence of triphenylphosphine in refluxing toluene under high-dilution conditions. 

Rioinelaidio aeid S-magnetic stirring bar are placed 360 mg (1.2 mmol) of ricinelaidic acid (see above), 308 mg (1.4 mmol) of 2,2 -dipyridyl disulfide (Note 5), 1 ml of benzene and 367 mg (1.4 mmol) of triphenylphosphine, and the mixture is stirred for 30 min. The resulting slurry is then dissolved in 55 mL of dry acetonitrile (Note 6). 

Triphenylphosphine/a,a -dipyridyl disulfide Active carboxylic acid esters by redoxesterification... 

Triphenylphosphine-carbon tetrachloride Triphenylphosphine with 0,0 -dinitro-diphenyldisulfide or with dipyridyl disulfide... 

Related Reagents. 2,2-Dipyridyl Disulfide (a reductive condensation reagent system with triphenylphosphine) )V Hydroxy-pyridine-2-thione. 

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